Although systems with a single magnetic element, not interacting with other magnetic elements, are easily manipulated, systems with multiple magnetic elements are currently uncontrollable due to their complex interactions. Attempts to control the ‘up’ or ‘down’ state of each magnetic element has only been successful for the magnetic element that is not interacting with another magnetic element. It is preferable to increase the density of magnetic devices to the point where a plurality of magnetic elements are in close enough proximity that they interact with each other. Once a plurality of magnetic elements begins to interact, the interaction not only complicates the system, but also makes changing the state of a single magnetic element seemingly impossible. The development of effective methods for the dynamic control of a plurality of magnetic element is key to the advancement of higher-density magnetic devices, which is highly desirable in for numerous magnetic devices, for example, magnonic crystals, nano-oscillators, magnetic random access memory and logic devices, preferably vortex based.
Vortices are observed in the statics and dynamics of a variety of physical systems, such as fluids and plasma, optics, superconductors and magnetic structures. In patterned mesoscopic ferromagnets, the ground state of the static magnetization can have a form of a vortex that consists of a large region of in-plane curling magnetization (clockwise or anticlockwise sense of rotation or chirality) and a small core region (˜10 nm) with out-of-plane magnetization, which can be pointing either up (+1) or down (−1) (positive or negative core polarity).
Magnetic data storage and logic devices, in general have the potential to provide higher speed, durability, low-power consumption and radiation resistant advantages over conventional products (semiconductor). Some of the conceptual designs incorporate magnetic vortices as the key element in its functionality. In this regard, lot of attention has been given to the fundamental research on vortex dynamics in confined magnetic geometries. So far, only conceptual research structures have been proposed for exploiting the fast-switching properties and storage bits capability of vortex cores. Their examples are magnetic random access memories, spin-torque nano-oscillators, magnetic storage and logic devices, and vortex-based magnonic crystals. For instance, magnonic crystals are the magnetic counterparts of photonic crystals and are theoretically proven to propagate signal information at a speed of few km/sec.